Mechanisms in mineral oil plasmacytomagenesis in the BALB/c mouse are being actively studied. The role of the oil granuloma and microenvironmental dependency are being studied in vivo in nu/nu mice, and an in vitro model is being developed. Attempts are being made to grow human myelomas in pristane-conditioned nu/nu mice. Work on the determining genetic basis of susceptibility continues with the development of a number of BALB/c-DBA/2 congenic strains, in which all available DBA/2 markers are put on the BALB/c background. The role of the LPS-C3H/HeJ gene and the nu/nu defect are also being tested. Attempts to isolate plasmacytomagenesis type C viruses are underway. An in vitro method of plasmacytoma induction is being employed using Abelson virus. Antigen binding activities of myeloma proteins continue with a search for myelomas with anti-idiotypic activity. Myeloma proteins are being screened with 250 other myeloma proteins to find interacting proteins (anti-idiotypes, anti-C-region markers).